Nant de Drance storage power plant

Nant de Drance SA is building a pumped storage power station in the Valais municipality of Finhaut. The facility will be situated in an underground cavern between the existing Emosson and Vieux Emosson reservoirs. The power station is designed to generate electricity at peak consumption times and to balance out the irregular and variable electricity generation from renewable energy sources.

When electricity consumption is high, the water from the Vieux-Emosson reservoir plunges down two 425 metre high vertical shafts into the underground power station. Here it drives turbines and is subsequently fed into the Emosson reservoir. In reverse, when the demand for electricity is reduced, the water from the Emosson reservoir is pumped back up to the Vieux-Emosson reservoir. Hence, the Nant de Drance power station is able to store the energy from the excess generation. With an output of 900 megawatts, the Nant de Drance power station will generate around 2.5 billion kWh of energy per year. The plant’s operator is HYDRO Exploitation SA.

Facts & figures

Plant type:

Storage power plant


Finhaut, Switzerland

Number of turbines:

6 Francis pump turbines


900 MW


39 %



Average annual production:

2,500 GWh

Guided tours:



Under construction